Boiler for the boiling and evaporation of liquids



Feb. 4, 1941. H. PAULING 2,230,412

BOILER FOR THE BOILING AND EVAPORATION OF LIQUIDS Filed Nov. 7, 1938 I s I I 2 r I 6- i F I I, 6

6 6 2 I 6 I 6 6 6 1 I 4 I L J 6 -Even7iu fidrgy PCZ/ZbZL iZ Q Patented Feb. 4, 1941 Unit BOILER FOR THE BOILING AND EVAPORA- TION OF LIQUIDS Harry Pauling, Berlin, Germany 8 Claims.

The properties of many liquids necessitate for the boiling and evaporation apparatus substances which are not suitable for the construction of tubes, nests of tubes and the like. This is particularly the case for cast iron and cast iron alloys, for example such as contain manganese and/or silicon. On this account for the boiling and evaporation boilers are indicated which in respect of their heating surface require a relatively large space.

In accordance with the present invention the efficiency of a boiler increases to an astonishing degree when the boiler is provided with one or more funnel-shaped inserts, open at the top and bottom, with the convergence directed upwards. A funnel-shaped insert is advantageously located where the bottom of the boiler joins the cylinrical jacket. The surface of the insert, which for passage of the vapour is advantageously provided with perforations, can be straight or curved and the edge of the insert is perforated or indented.

The advantageous effect of the funnel-shaped 25 insert is due according to the discoveries of the inventor to the fact that by means of the insert the circulation of the liquid in the boiler is interrupted. In a customary boiler of large diameter and corresponding height by far the majority of 30 the vapour is produced on the jacket; the vapour streams upwards along the jacket and entrains liquid up to the liquid surface where the liquid separates from vapour and then streams downwards towards the middle of the boiler. In the middle portion of the boiler therefore the liquid streams downwards to the middle of the bottom of the boiler and from there again to the jacket. The liquid circulation produced in this manner in the boiler is so great that the bottom surface is only sufiiciemt for warming the liquid but not for causing vaporisation thereof, which is understood from the following calculation.

In the case of a boiler of for example 3 metres diameter and 3 metres height and a specific gravity of the liquid of about 1.8 (in this case 96% sulphuric acid is assumed) the pressure difference between the liquid surface and the bottom of the boiler is about 0.54 atmos; if the pressure at the top is l atmos. then the pressure at the bottom is 1.54 atmos; the boiling point at the top is 315 (3., at the bottom 335 C. Since the specific heat of the 96% sulphuric acid is 0.35 then every kilo of acid on streaming along the boiler bottom from the middle to the side takes up a quantity of heat of (335-315) x0.35='7 kg. cal. If the heat (Cl. 23274i) transfer for the case of the fire gases to slowly streaming liquid is assumed to be about 1,500 kg. cal./m. /h., then the 7 m? of bottom surface transmit 105,000 kg. ca-l./h.; this quantity of heat corresponds to 15,000 kg. acid circulation per hour or about 8,300 litres per hour.

If according to the invention by the arrangement of a funnel-shaped insert the liquid circulation is interrupted, the eficiency of the boiler 10 increases considerably because also at the bottom a considerable vaporisation sets in and the vaporisation of the liquid has a very much better heat transfer coeflicient than the Warming up of the liquid. By practical experiments it has been ascontained that for example the efliciency of a sulphuric acid concentration boiler can by the incorporation of a funnel-shaped insert be raised from 14 tons to tons per day.

The development of vapour bubbles at the hot. 20 tom has the further advantage that no salts, sludge or other substances can deposit on the bottom; on this account the undesired incrustations are avoided which are frequently the cause of over-heating, boiling With bumping or even burning through of the boiler bottom.

The funnel-shaped inserts further have the effect that the vapours evolved from the boiling liquid are distributed throughout the whole liquid content, in particular in the middle portions of the boiler cross section, Where otherwise no turbulence of the liquid by vapour bubbles takes place, so that boiling delays no longer occur.

The invention is illustrated in the accompanying drawing in which Figure 1 shows a boiler with a. flat or curved bottom and Figure 2 a boiler the bottom of which is conically constructed, that is to say is: drawn out to a long acute cone.

The flat or curved bottom of the boiler according to Figure 1 is indicated by I, the cylindrical jacket by T. The funnel-shaped insert is shown at 2. Its convergence is upwardly directed and it is located with its lower edge 5 at the point where the curved bottom I joins the cylindrical jacket 1. The edge 5 of the insert 2 is perforated or indented; the surface of the insert, which according to the drawing is straight can also be curved and for the passage of the vapour is provided with perforations 6.

According to Figure 2 in the conically constructed boiler bottom, which is drawn out to a long acute cone, indicated by I, three funnelshaped inserts 2, 3 and 4 are arranged the surfaces of which likewise provided with perfora- 2. A boiler as claimed in claim 1, having a bottions 6 for the passage of the vapour and the edge 5 of which is perforated or indented.

It may be remarked that the conical construction of the boiler bottom itself has the advantage that in this part of the boiler, which lies in the hottest zone of the fire, a strong evolution of vapour takes place. On this account the deposition of salts, sludge and. other substances is avoided. The conical form of the boiler bottom has the further result that the vapour, which is the most effective and moreover an indifferent stirring means, is distributed in the space located in the middle of the boiler, where frequently on account of unsatisfactory stirring boiling delays take place.

These effects are increased by the arrangement of one or more funnel shaped inserts which are open at the top and bottom and have the convergence directed upwards, in the conical portion of the boiler.

If the evaporation or boiling process necessitates the passage of gases or steam, or if the heating is solely by means of steam, it is to be recommended to arrange the inlet for the gases or the heating steam at the apex of the conical portion of the boiler.

I claim:

1. A boiler for the concentration of sulphuric acid and liquids of similar properties having a bottom and a cylindrical wall and an insert for controlling the circulation of the liquid undergoing concentration, said insert being in the shape of a truncated cone which is open at the bottom, said insert also having an opening at the top for the circulation of liquid therethrough which has a diameter not less than one-tenth the diameter of the boiler, the inclined wall of the cone making an angle of approximately 45 with the wall of the boiler and the height of the cone being not greater than half the height of the boiler.

tom of curved formation.

3. A boiler as claimed in claim 1, in which the insert is provided with perforations.

4. A boiler as claimed in claim 1, in which the base of the insert has the same diameter as the inside diameter of the boiler and is located at the junction of the wall of the boiler and the bottom, there being a plurality of notches cut in the lower rim of the insert.

5. A boiler as claimed in claim 1, in which the bottom has the shape of a long acute cone, and in which an additional insert is provided between the end of the cone and the point where it joins the wall of the boiler.

6. A boiler for the concentration of sulphuric acid and liquids of similar properties having a cylindrical wall and a bottom in the form of a long acute cone, together with an insert for controlling the liquid circulation in the boiler, said insert being in the shape of a frustrum of a cone, open at the top and bottom, and having its base located at the junction of the cylindrical wall of the boiler with the conical bottom thereof.

7. A boiler as claimed in claim 6, which is provided with a plurality of superimposed inserts of progressively increasing diameter located at spaced intervals along the inside of the conical bottom of the boiler.

8. A boiler for the concentration of sulphuric acid and liquids of similar properties, said boiler having a bottom in the form of a long acute cone, together with a plurality of spaced inserts for controlling the liquid circulation in the boiler, 3 each insert being in the shape of the frustrum of a cone, open at the top and bottom, and each insert having its base located along the conical bottom of the boiler.

HARRY PAULING. 

